在服务器计算机上调用await webClient.DownloadDataTaskAsync(url);时遇到问题。我使用这段代码通过ImageProcessor
url下载裁剪的图像
这是我的代码：
public async Task<Stream> GetStreamFromUrlAsync()
{
byte[] imageData = null;
using (var webClient = new System.Net.WebClient())
{
try
{
imageData = await webClient.DownloadDataTaskAsync(url);
}
catch (HttpRequestException e)
{
throw new HttpRequestException("Error When Downloading Image inner : " + e.Message, e);
}
}
return new MemoryStream(imageData);
}
在Controller中使用以上方法：
[HttpPost]
public async Task<ActionResult> CropImage(UploadImage data)
{
// some code for getting path
Bitmap img = new Bitmap(await data.GetStreamFromUrlAsync());
img.Save(path);
}
在本地计算机上一切正常，但在服务器计算机上收到以下错误消息：
这是通过堆栈跟踪的完整错误消息：
ErrorMessage: The underlying connection was closed: An unexpected error occurred on a send.
InnerException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
StackTrace: at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
at System.Net.WebClient.GetWebResponse(WebRequest request, IAsyncResult result)
at System.Net.WebClient.DownloadBitsResponseCallback(IAsyncResult result)
End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at codetiMAit.BLL.UploadImage.<GetStreamFromUrlAsync>d__105.MoveNext() in D:\codes\prjs\BLL\UploadImage.cs:line 71
End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)
at codetiMAit.Controllers.LoginController.<CropImage>d__21.MoveNext() in D:\codes\prjs\Controllers\LoginController.cs:line 894
End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Web.Mvc.Async.TaskAsyncActionDescriptor.EndExecute(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass8_0.<BeginInvokeAsynchronousActionMethod>b__1(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__11_0()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass11_1.<InvokeActionMethodFilterAsynchronouslyRecursive>b__2()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass7_0.<BeginInvokeActionMethodWithFilters>b__1(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass3_6.<BeginInvokeAction>b__3()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass3_1.<BeginInvokeAction>b__5(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult)
at System.Web.Mvc.Controller.<>c.<BeginExecuteCore>b__152_1(IAsyncResult asyncResult, ExecuteCoreState innerState)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
at System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult)
at System.Web.Mvc.Controller.<>c.<BeginExecute>b__151_2(IAsyncResult asyncResult, Controller controller)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
at System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult)
at System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult)
at System.Web.Mvc.MvcHandler.<>c.<BeginProcessRequest>b__20_1(IAsyncResult asyncResult, ProcessRequestState innerState)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult)
at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
at System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult)
at System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result)
at System.Web.HttpApplication.CallHandlerExecutionStep.InvokeEndHandler(IAsyncResult ar)
at System.Web.HttpApplication.CallHandlerExecutionStep.OnAsyncHandlerCompletion(IAsyncResult ar)
服务器计算机：Windows Server 2012 .net Framework 4.7.1和。
我找到了一些解决方案，但没人为我工作，例如，我这样做：
static MyController()
{
ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls;
}
和：
webClient.Headers.Add("Connection", "Keep-Alive");
webClient.Headers.Add("Keep-Alive", "3600");